确保用户在使用 BMI Analyzer 时仅输入整数

Question

# This program calculates a person's BMI after
# user inputs their height and weight, it then converts
# the data from inches to meters and pounds to kilograms.
# Based on findings the program displays persons BMI


# Display welcome message.

print( "Welcome to My BMI Calculator \n " )

# Ask the user to input their name.

persons_name = input( 'Name of person that we are calculating the BMI for: ' )

# Ask for the user's height in inches.

inches = float(input( 'Supply Height in Inches: ' ))

# Ask for the user's weight in pounds.

pounds = int(input( 'Supply Weight in Pounds: ' ))

# Convert from inches to meters

inches_to_meters = float(inches / 39.36)

# Convert from pounds to kilograms

pounds_to_kilograms = float(pounds / 2.2)

# Calculate the person's BMI

BMI = float(pounds_to_kilograms / ( inches_to_meters * inches_to_meters ))

# Display the BMI

print( persons_name, 'BMI is:'  , format(BMI, '.2f' ))

# Display person's BMI findings based on the given data

if BMI <= 18.50:
print( 'BMI finding is the subject is: Underweight ' )
elif BMI > 18.51 < 24.90:
print( 'BMI finding is the subject is: Normal ' )
elif BMI > 24.91 < 29.90:
print( 'BMI finding is the subject is: Overweight ' )
elif BMI > 29.90:
print( 'BMI finding is the subject is: Obese ' )

如果我将此代码粘贴到此处后格式错误，我提前道歉。如果它错了，请告诉我，以便我在这个网站上学习如何正确格式化它。据我了解，我每行缩进 4 个空格。

这是一个 BMI 分析程序，它以英寸为单位获取人的身高并将其转换为米，以磅为单位获取人的体重并将其转换为公斤。

经过测试，它似乎可以工作，但前提是您输入整数。因此，如果您输入 0 表示体重或输入 0 表示身高，则不会出现错误，而是会在 BMI 计算中使用该数字。

我的问题是：我如何确保用户只输入实数、没有负数或带小数点的数字，如果输入，显示和错误提示“仅使用整数”

Answer 1

使用try...except 语句。
这些语句用于尝试程序员认为可能有错误的一段代码。然后，程序员“捕获”错误（如果有）。
在您的情况下，输入的数字应该是自然的（不是整数，因为身高为零的 BMI 计算不正确）。

因此，代码将是：

print("Welcome to My BMI Calculator.\n")
persons_name = input("Name of person that we are calculating the BMI for: ")
try:
    inches = int(input("Enter height in inches: "))
    assert inches > 0
    inches_to_meters = inches / 39.36
    pounds = int(input("Enter weight in pounds: "))
    assert pounds > 0
    pounds_to_kilograms = pounds / 2.2
    BMI = pounds_to_kilograms / (inches_to_meters ** 2)
    print(persons_name, "BMI is:", format(BMI, ".2f" ))
    if BMI <= 18.50:
        print( 'BMI finding is the subject is: Underweight ' )
    elif 18.51 < BMI <  24.90:
        print( 'BMI finding is the subject is: Normal ' )
    elif 24.91 < BMI <  29.90:
        print("BMI finding is the subject is: Overweight")
    elif BMI > 29.90:
        print("BMI finding is the subject is: Obese")
except ValueError:
    print("Enter only natural numbers!")
except AssertionError:
    print("Enter positive numbers only!")

Answer 2

一个简单的while循环应该适合你：

inches=float(input('Height in inches:'))
while (inches<0)|(inches%1!=0):
    inches=float(input('error, use whole numbers only:'))
inches = int(inches)

Height in inches:5.2

error, use whole numbers only:-182

error, use whole numbers only:180
180

Answer 3

去掉float()输入转换试试：

x=input()
try: 
   int(x) 
except: 
   raise ValueError('Cannot accept:', x)

还强烈建议您将代码拆分为函数。